Rising water is an underappreciated driver of forest mortality

Forests are experiencing death not just from drought and fire, but also from rising water levels. Across the globe, as the atmosphere warms, both droughts and floods are becoming more prolonged and severe. While the consequences of drought-induced tree deaths and wildfires are well-documented, the impact of inundation on forests has been largely overlooked.

Employing high-resolution aerial imagery and artificial intelligence, researchers analyzed over 260 million dead trees in the United States' Great Lakes region and coastal areas from 2012 to 2023. Within a 10-kilometer radius of the coast, over half of the mapped forest mortality was concentrated within just 10% of the forests, particularly in high-elevation wetlands and low-lying regions prone to flooding.

Mortality rates more than doubled in a decade around growing freshwater lakes and in inland wetlands experiencing intensified precipitation, while they tripled in coastal forests where rising sea levels combined with salinization exacerbated inundation. These findings reveal that rising waters are a widespread and underrecognized cause of forest decline, potentially extending far inland.

This underscores the urgent need to reconsider the effects of climate change on the health and function of the world's most carbon-dense forests as seas rise and global hydroclimate patterns shift.